Will Hainan Airlines provide me with a new shrink-wrapped blanket or should I take my own?

I checked the web site for Hainan and they say:

To make your flight even more comfortable and convenient, we have carefully selected a series of items for you to use, including soft and comfortable blankets and fluffy waist pillows, allowing you to relax your entire body and enjoy a splendid journey.

There is no mention of whether the blankets are shrink-wrapped. If this is important to you, or if the blankets not being loaded would ruin the flight for you, consider bringing your own. But not a huge bed blanket from home. You can buy special travel blankets that fold up small. I use a pashmina, because silk folds really small and it's warm, plus I can use it for other purposes during my trip.

Bring your own! Blankets and pillows are not always washed between uses, even if they're in plastic. There are many travel blankets, or small polar fleece blankets, to use instead. Depending on the season, could you just use your coat?

A cheap option I've done is to buy a meter or so of polar fleece from a fabric store, roll it into a tiny bag, and use that. It is also very easy to wash after the flight.